Some years ago, in the 1980s and 1990s, we witnessed a heated debate around the Gaia hypothesis as proposed by J. Lovelock (1978, 1989). The fuss was nourished by the fact that about the same time the “selfish gene” concept announced itself in neo-Darwinism. The two views could not be more remote. If we want to show in this book that one of the basic features of life is “being-together”, we should devote a chapter to the Gaia theory, especially when – as we believe – the Gaian mode of affairs has prevailed throughout the history of life.
scholar: You spoke of ‘a’ region in which everything returns to itself. Strictly speaking, a region for everything is not one region among many, but the region of all regions.
teacher: You are right; what is in question is the region.
scientist: And the enchantment of this region might well be the reign of its nature, its regioning, if I may call it that.
scholar: It seems a region holds what comes forward to meet us. [ … ] So the region itself is at once an expanse and an abiding. It abides into the expanse of resting. It expands into the abiding of what has freely turned towards itself. In view of this usage of words, we may also say ‘that-which-regions’ [Gegnet] in place of the familiar ‘region’ [Gegend].
Heidegger 1966, 65–66
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Notes
- 1.
There may be a technical drawback here, however, in that the phenomenon of Gaian feedback might encounter difficulties when it comes to its reification. It is one thing to have a circuit with one or several sensors and effectors, and another to have billions of them as in case of the biosphere. How can they be coordinated into concert of a single integrated system? What is the nature of the wiring and setting mechanisms for all these tiny elements? We shall not follow this particular problem further and will take Gaia as if it consisted of a single regulator – single effector circuit.
- 2.
By using “prokaryotes” we encompass both kingdoms living today (Bacteria and Archaea), as well as any possible prokaryote-like forms that might have lived in the past.
- 3.
Just for the sake of this historical aspect, and for simplicity, we shall mostly focus on just the prokaryotic biosphere here. In contemporary communities, however, eukaryotes play an inseparable role as well. For example, soil communities cannot be understood without also taking into consideration protists, fungal mycelia, and the plant rhizosphere. It is believed, however, that pure prokaryotic communities are some 2 billion years older than the mixed ones of today, and the type of information processing necessary for a Gaian economy is their invention.
- 4.
The definition is based on the fact that double-stranded molecule of DNA when heated to about 90°C dissociates into single strands (melting); the temperature is typical for a given specimen. When the sample is cooled again, the strands tend to re-associate and zip into double-stranded form again. Theoretically, if such a re-associated sample is re-heated, it will melt at the same temperature as before. In practice, not all strands will find their counterpart and re-association will be incomplete, with many partial zippings or mismatches, or with single strands left without complements. (Therefore we find a 70% limit for re-associated strands) Such incomplete and mismatched strands will be more unstable and will melt at lower temperature when heated again – therefore the melting point of the sample will be lower than originally, but by no more than 5°C. If, however, two samples from different sources are mixed (e.g. isolated DNA from two species, cut it into suitable portions), many more mismatch events will occur, and both the re-association percentage and melting point decrease will go beyond the limits just stated.
- 5.
Compare with the magic number 98, indicating the percentage of identity in genomes of humans and chimps.
- 6.
Nucleotide frequency: bacterial species have a typical average ratio of (A+T)/(G+C) in their genomic DNA. Have a species characterized, say, as having 40% average content of G+C; if you find, within the genome, a segment containing 65% of these bases, then the suspicion arises that the segment might have been acquired recently, from another species for which high GC content is typical.
Codon usage: In protein-coding areas of the genomes (open reading frames, ORF) the sequence of amino acids in proteins is coded by nucleotide triplets. The code is, however, degenerate for most amino acids: some may be coded for by as many as 6 different triplets. It does not follow that all possibilities are ordinarily used in a given species – usually 1–2 codons are preferred in such cases. If an ORF with atypical codon usage is found in a genome, it may indicate a recent transfer from a source characterized by different codon preferences.
- 7.
Chromosome: the main genetic thesaurus of bacteria – usually its “length” is of the order of millions of nucleotides. Plastid: non-chromosomal pieces of DNA (tens of thousands nucleotides long) which co-exist and replicate independently of the chromosome, and which can be readily exchanged with other calls. They can also be incorporated into the chromosome.
- 8.
Examples: the family of homoserine lactones or special oligopeptides. Note that such molecules are not metabolites but genuine signals fulfilling semiotic functions – like hormones and pheromones in eukaryotes.
- 9.
For example, gene expression in the intestinal epithelia will respond to the needs of symbionts by producing special nutrients in the intestinal mucus. Germ-free animals maintained in the laboratory differ from normal inhabitants of Gaia in both gene expression and mucus composition (and must be fed by many extra nutrients to survive).
- 10.
Structures consisting of points and connecting lines are ubiquitous in many scientific fields. In mathematics they are called “graphs”, with the points described as “vertices” and the lines as “edges”; in computer science they are usually called “networks” with “nodes” and “links” or “connections”; in physics such structures are “systems”, which have “sites” and “bonds”; and finally, in sociology one usually refers to a network of people, or “actors”, and contacts, friendships, or “ties”.
- 11.
“Small diameter” suggests that that the diameter should grow logarithmically with the size of the graph; “heavy clustering” means that the clustering coefficient will not diminish when the graph grows, i.e. the number of edges per node remains constant.
- 12.
If you are a bird you can improve some particular way of flying, but you cannot fly across the valley and join bats who are struggling to improve on another neighbouring peak.
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Markoš, A., Grygar, F., Hajnal, L., Kleisner, K., Kratochvíl, Z., Neubauer, Z. (2009). The Living Planet. In: Life as Its Own Designer. Biosemiotics, vol 4. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-9970-0_5
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